The instant invention relates to electrical switches and more particularly to a durable slide switch which is operative with a crisp, positive switching action.
Electrical slide switches wherein a slide member is slidably repositionable to affect a switching action have been found to be effective for a wide range of electrical switching applications, such as in small tools and appliances, and as a result, over the years, a wide variety of different types of electrical slide switches have been developed for use in such applications. In this regard, however, for most applications, it has generally been found that in order for a slide switch to be effective, it should be durable enough to withstand repeated use over a prolonged period of time. Further, a slide switch should be operative with a crisp, positive switching action for making and breaking contact without arcing. Still further, a slide switch should be resistant to dielectric breakdown, and it should be adapted to be readily and easily installed in various tools, appliances, and other devices.
The switches disclosed in the U.S. patents to Bramming U.S. Pat. Nos. 1,740,535; Hill 2,303,693; Geci 2,550,145; Hathorn et al 2,762,880; and Marquardt 3,767,870 are generally illustrative of the types of the electrical slide switches which have been heretofore available and represent the closest prior art to the subject invention of which the applicant is aware. However, since these switches fail to suggest the novel features of the slide switch of the instant invention which enable it to be reliably operated with a crisp, positive switching action, they are believed to be of only general interest with respect thereto.
The instant invention provides a highly reliable and durable slide switch which is operative with a crisp, positive switching action and which is resistant to dielectric breakdown and adapted for use in a wide variety of switching applications. More specifically, the switch of the instant invention comprises a housing which is preferably made of a nonconductive plastic material, spaced, substantially aligned first, second and third fixed contacts in the housing, a movable contact member in the housing, and a slide member which is slidable between a first position and a second position for slidably moving the movable contact member between a first position wherein it is in engagement with the first and second fixed contacts but in spaced disengagement from the third fixed contact and a second position wherein it is in engagement with the second and third fixed contacts but in spaced disengagement from the first fixed contact. The movable contact is integrally formed from a resilient conductive sheet metal, and it includes an elongated contacting portion and first and second biasing portions which extend from the opposite ends of the contacting portion. The biasing portions include inwardly extending portions which are spaced from the contacting portion and extend inwardly in converging relation from the opposte ends of the contacting portion to bends and outwardly extending portions which are spaced from the inwardly extending portions and extend outwardly in diverging relation from the bends. The switch is further constructed so that the slide member engages the outwardly extending portions of the biasing portions to maintain either or both of the biasing portions in slightly resiliently compressed dispositions in order to resiliently bias the contacting portion toward the appropriate fixed contacts. The contacting portion preferably has a substantially centrally disposed bump thereon which extends in the direction of the fixed contacts and passes over the second fixed contact when the movable contact member is moved between the first and second positions thereof in order to pivot the contacting portion slightly as it is moved between the first and second positions thereof so that the contacting portion breaks contact with one of the first or third fixed contacts well before it makes contact with the other. In addition, the switch preferably comprises first and second pairs of detent elements for alternatively releasably retaining the slide member in the first and second positions thereof. In this connection, one of the detent elements of each pair is preferably formed on the slide member, and the other detent element of each pair is preferably formed on the housing, and the detent elements on the housing are preferably spaced apart by a greater distance than the detent elements on the slide member. Further, the detent elements are preferably positioned so that both pairs of the detent elements are in partially disengaged positions when the bump on the contacting portion passes over the second fixed contact and so that one pair of the detent elements is still in a partially engaged position when the other pair of detent elements is moved into a fully engaged position as the slide member is moved between the first and second positions thereof. The switch of the instant invention is adapted to be alternatively constructed as either a single-pole, double-throw switch or as a double-pole, double-throw switch, and when it is embodied as a double-pole, double-throw switch, it includes first and second spaced, substantially parallel sets of first, second and third fixed contacts in the housing and first and second movable contacts which are slidable between first positions thereof wherein they are in engagement with the first and second fixed contacts and second positions thereof wherein they are in engagement with the second and third fixed contacts. Further, when the switch is embodied in a double-pole, double-throw configuration, it preferably includes a track which separates the first and second sets of fixed contacts, and the first and second movable contacts travel on opposite sides of the track and are guided by the track in their movement across the first and second sets of fixed contacts, respectively.
It has been found that the switch of the instant invention has significant advantages over the heretofore available switches, such as those disclosed in the hereinabove cited references. Specifically, the biasing portions of the movable contact member of the switch of the instant invention are constructed so that they can be repeatedly compressed and flexed as the contacting portion of the movable contact member is moved between the first and second positions thereof without causing the biasing portions to lose their resiliencies. Further, because of the configurations of the biasing portions, the bump on the contacting portion of the contact member causes the contacting portion to pivot as the bump passes over the second fixed contact so that a "break-before-make" action is effectively achieved in the switch of the subject invention. Still further, the first and second pairs of detents cooperate to enhance the crisp snap-action of the switch as it is moved between the first and second positions thereof, and they effectively prevent the slide member from becoming "stalled" in an intermediate position.
Accordingly, it is a primary object of the instant invention to provide an improved slide switch which can be repeatedly operated with a high degree of effectiveness over a prolonged period of time.
Another object of the instant invention is to provide a slide switch having a sharp, crisp switching action.
An even further object of the instant invention is to provide an effective slide switch which is not prone to arcing during switching.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.